The present invention relates generally to a writing instrument. More specifically, this invention relates to a free ink writing instrument that permits smooth flow of ink when in use and prevents leaking by using nano-technology.
Writing instruments are widely used in daily life with various functions and designs. Besides the common pencils, ball point pens and fountain pens, there is a type of pen having a free ink direct supply system, such as a pen having a relatively large nib that is used for marking/drawing, e.g., markers, sign pens.
Such a pen typically includes a penholder having an ink reservoir therein, and a marking tip which draws ink from the ink reservoir by capillary action. However, in the pen, as the ink in the ink reservoir is consumed, the pressure in the ink reservoir drops and air must be accordingly introduced therein. If the air cannot enter the ink reservoir to relieve the pressure difference, the ink flow may be interrupted. On the other hand, if the air in the ink reservoir expands due to changes in temperature, atmospheric pressure, and the like, the ink may drip/leak from the marking tip.
In order to control the pressure in the ink reservoir, one solution is to provide an air venting system in the pen that controls air pressure, so as to provide a steady flow of ink when writing and to prevent the pen from leaking ink. Conventionally, such an air venting system is formed by use of a piston, a valve or a capillary structure. However, such an air venting system has a relatively complicated structure. Further, the pen with such an air venting system can easily malfunction and has an unsatisfactory writing outcome, i.e., unstable ink flow and/or ink leakage when writing.
As the problem of pressure balance cannot be well solved, other methods also have been widely used in the industry. For instance, a marking pen may contain a fibrous core that absorbs and holds ink, and a nib in communication with the fibrous core to obtain an ink supply, so that it can be used for writing purposes. The nib is formed from a fiber capable of performing capillary action. However, such pen normally uses a poor performance fibrous core to hold the ink, thus affecting the ink flow and causing waste of the ink.
Therefore, there is a need to provide a free ink writing instrument that permits a smooth flow of ink and prevents leaking with an improved pressure balance system. In addition, the writing instrument has a relatively reasonable cost in manufacturing.
To overcome the limitations of the related art described above, and to overcome other limitations that will become apparent upon reading and understanding the present specification, this invention is directed to a writing instrument for smooth ink flow and/or against dripping/leaking. The writing instrument of the present invention uses nano technology, i.e., nano hydrophobic venting material, to permit air flow into and out of the ink reservoir to control pressure balance between the ambient atmosphere and the interior of the reservoir while preventing ink leaking to the atmosphere. Thus, the writing instrument can have a continuous steady flow of ink without leaking.
In one embodiment, the writing instrument includes a housing means containing an ink reservoir therein, a writing nib in communication with one end of the ink reservoir, and a pressure balance system in connection with the other end of the ink reservoir. The pressure balance system has a nano hydrophobic venting sheet that permits air flow into and out of the reservoir to compensate pressure differentials between the ambient atmosphere and the interior of the reservoir, and prevents ink flow from the reservoir to the atmosphere.
Further, in one embodiment, the pressure balance system includes a control valve, a washer, the nano hydrophobic venting sheet and a vent-plug arranged in that order. The control valve is in communication with the reservoir, and allows air flow and blocks ink leaking from the rear end of the housing. The vent-plug is used for venting the reservoir to atmosphere. With the high performance of the nano hydrophobic venting sheet, the pressure balance system maintains pressure balance between the interior of the reservoir and ambient atmosphere in various situations (e.g., changes in temperature/atmosphere pressure, ink consumption, etc.). Thus, the writing instrument having a smooth ink flow without leaking/dripping can be obtained.
Further, in one embodiment, the writing instrument has at least one writing nib, each of which draws ink from the reservoir through one ink guiding system. Also, each writing nib further couples to one pressure balance system for air venting.
Yet, in one embodiment, the pressure balance system further includes an air duct, a vent block, and a vent-plug disposed within the vent block. Air in the reservoir communicates with atmosphere through the air duct, the vent block and the vent-plug.
Furthermore, in one embodiment, the writing nib has a fibrous tip or a metal tip.
Moreover, in one embodiment, the writing instrument includes a cap fitting with the housing. The cap surrounds the writing nib and forms an air tight seal when in sealing engagement with the housing.
A variety of additional advantages of the invention will be set forth in part in the description which follows, and in part will be obvious from the description, or may be learned by practice of the invention. Various advantages of the invention will be realized and attained by means of the elements and combinations particularly point out in the claims. It is to be understood that both the foregoing general description and the following detailed description are exemplary and explanatory only and are not restrictive of the invention as claimed.